Welbeck joined the United academy as an eight-year-old but was sold by Van Gaal in September to make way for Falcao.

While the Colombian has struggled for form since moving to Old Trafford, Welbeck reminded United fans of his qualities on Monday evening by scoring the winner in Arsenal’s 2-1 FA Cup quarter-final victory.

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Asked whether he had any regrets over trading Welbeck for Falcao, an agitated Van Gaal said: "He (Falcao) has scored four goals, had three or four assists and he stimulates the other players, so that is an aspect of the profession. But it is now easy for you to say that and you are happy to say that."

Welbeck’s winner came after an error from Antonio Valencia as his underhit backpass was seized upon by the forward on the hour mark.

"It’s very disappointing when you give the victory to your opponent," said Van Gaal. "When you haven’t lost because of the opposition, you have lost because of yourself.

"The players are very disappointed because they know that it could be different. Matches are decided by goals and you see the second goal, it was nothing, we gave it away. The man who did that was the best man of my team and that’s also disappointing for him."